Propagation of pacemaker activity in the guinea-pig antrum.

摘要: Cyclical periods of depolarization (slow waves) underlie peristaltic contractions involved in mixing and emptying contents the gastric antrum. Slow waves originate from a myenteric network interstitial cells Cajal (ICC-MY). In this study we have visualized sequence propagation Ca2+ transients associated with pacemaker potentials ICC longitudinal (LM) circular muscle (CM) layers isolated guinea-pig Gastric antrum was dissected to reveal ICC-MY network, loaded Fluo-4 AM activity monitored at 37°C. propagated throughout an average velocity 3.24 ± 0.12 mm s−1 frequency 4.87 0.16 cycles min−1 (n= 4). The wave often appeared ‘step-like’, separate regions being activated after variable delays. direction highly (Δ angle 44.3 10.9 deg per cycle) not confined axes or muscle. spread out radially site initiation. initiating correlated secondary intramuscular interstial Cajal, ICC-IM, smooth cells, local distortion (contraction) field view. TTX (1 μm) had little effect on slow potential activity, but 2-APB (50 blocked all waves, indicating pivotal role for intracellular stores. Nicardipine (2 eliminated transient generated by muscle, did affect fast upstroke ICC-MY. These results indicate that follow activation, beginning ICC-IM followed later sustained is responsible contraction.